First of all, thank you so much for helping me out.
Thanks to you I got through the first issue I wrote about.
Unfortunately, there is a new issue.
After the first issue, the system's been downloading new updates, until I encountered
Some update files are missing or have problems. We'll try to download the update again later. Error code: (0x80070003)
I keep hitting "Retry" but nothing is changing....
Every time I "Retry", it keeps installing
2021-06 x64 기반 시스템용 Windows 10 Version 20H2에 대한 누적 업데이트(KB5003637)
I tried the 3 solutions you suggested for the first issue (Additional troubleshooters, and Background Intelligent Transfer Service and Windows Update in Services.msc.)
By the way BITS and Windows Update in Services.msc turns on and off, I'm sorry, but I have no idea why....
KB5003637 is "Pending restart" again.
I'm hoping you could help me out one more time.
Thank you sincerely.